The disclosure relates generally to installation tools and methods for terminating one or more optical fibers with a fiber optic connector, and more particularly to such installation tools and methods having a camming member for actuating a portion of the fiber optic connector to secure the fiber optic connector to the one or more optical fibers.
Optical fibers are useful in a wide variety of applications, including the telecommunications industry for voice, video, and data transmission. Due at least in part to the extremely wide bandwidth and the low noise operation provided by optical fibers, the variety of applications in which optical fibers are being used is continuing to increase. For example, optical fibers no longer serve merely as a medium for long distance signal transmission, but are being increasingly routed directly to the home and, in some instances, directly to a desk or other work location.
In a system that uses optical fibers, there are typically many locations where one or more optical fibers need to be optically coupled to one or more other optical fibers. The optical coupling is often achieved by fusion splicing the optical fibers together or by terminating the optical fibers with fiber optic connectors. Fusion splicing has the advantage of providing low attenuation, but can make reconfiguring the system difficult, typically requires expensive tools to perform the operation, and involves additional hardware to protect the spliced area after the operation. Termination, on the other hand, provides the flexibility to reconfigure a system by allowing optical fibers to be quickly connected to and disconnected from other optical fibers or equipment.
One challenge associated with termination is making sure that the fiber optic connectors do not significantly attenuate, reflect, or otherwise alter the optical signals being transmitted. Performing termination in a factory setting (“factory termination”) is one way to address this challenge. The availability of advanced equipment and a controlled environment allow connectors to be installed on the end portions of optical fibers in an efficient and reliable manner. In many instances, however, factory termination is not possible or practical. For example, the lengths of fiber optic cable needed for a system may not be known before installation. Terminating the cables in the field (“field termination”) provides on-site flexibility both during initial installation and during any reconfiguring of the system, thereby optimizing cable management. Because field termination is more user-dependent, fiber optic connectors have been developed to facilitate the process and help control installation quality.
One example of such a development is the UNICAM® family of field-installable fiber optic connectors available from Corning Cable Systems LLC of Hickory, N.C. UNICAM® fiber optic connectors include a number of common features, such as a mechanical splice between a preterminated fiber stub (“stub optical fiber”) and an optical fiber from the field (“field optical fiber”), and are available in several different styles of connectors, such as ST, SC, and LC fiber optic connectors. FIGS. 1B and 1B illustrate an exemplary fiber optic connector 10 belonging to the UNICAM® family of fiber optic connectors. A brief overview of the fiber optic connector 10 will be provided for background purposes. It should be noted, however, that the apparatuses and methods disclosed herein may be applicable to other fiber optic connectors that are actuated in some manner to help establish a splice connection with one or more optical fibers.
As shown in FIGS. 1A and 1B, the fiber optic connector 10 includes a ferrule 12 received in a ferrule holder 16, which in turn is received in a connector housing 19. The ferrule 12 defines a lengthwise, longitudinal bore for receiving a stub optical fiber 14. The stub optical fiber 14 may be sized such that one end extends outwardly beyond a rear end 13 of the ferrule 12. The fiber optic connector 10 also includes a pair of opposed splice components 17, 18 within the ferrule holder 16, a cam member 20 received over a portion of the ferrule holder 16 that includes the splice components 17, 18, a spring retainer 22 fixed to the connector housing 19, and a spring 21 for biasing the ferrule holder 16 forwardly relative to the spring retainer 22 and connector housing 19. At least one of the splice components 17, 18 defines a lengthwise, longitudinal groove for receiving and aligning the end portion of the stub optical fiber 14 and an end portion of a field optical fiber 15 upon which the fiber optic connector 10 is to be mounted. An index-matching material (e.g., index-matching gel) may be provided within this groove for reasons mentioned below.
To mount the fiber optic connector 10 on the field optical fiber 15, the splice components 17, 18 are positioned proximate the rear end 13 of the ferrule 12 such that the end portion of the stub optical fiber 14 extending rearwardly from the ferrule 12 is disposed within the groove defined by the splice components 17, 18. Thereafter, the end portion of the field optical fiber 15 can be inserted through a lead-in tube (not shown in FIGS. 1A and 1B) and into the groove defined by the splice components 17, 18. By advancing the field optical fiber 15 into the groove defined by the splice components 17, 18, the end portions of the stub optical fiber 14 and the field optical fiber 15 make physical contact and establish an optical connection or coupling between the field optical fiber 15 and the stub optical fiber 14. The index-matching material (e.g., index-matching gel) provided within the groove surrounds this optical connection to help reduce losses in optical signals that are transmitted between the filed optical fiber 15 and stub optical fiber 14.
The splice termination of the fiber optic connector 10 is completed as illustrated in FIG. 1B by actuating the cam member 20, which engages a keel portion of the lower splice component 18 to bias the splice components 17, 18 together and thereby secure the end portions of the stub optical fiber 14 and the field optical fiber 15 within the groove defined by the splice components 17, 18. This step is typically completed using a specially-designed installation tool. The cable assembly may then be completed, for example, by strain relieving a buffer 25 of the field optical fiber 15 to the fiber optic connector 10 in a known manner.
FIGS. 2-4 illustrate an installation tool 30 that is an example of those offered by Corning Cable Systems for mounting the UNICAM® family of fiber optic connectors upon the end portion of a field optical fiber. Similar to the description above for the fiber optic connector 10, a brief overview will be provided for background purposes with the understanding that the systems and methods disclosed later herein are applicable to other types of installation tools. Indeed, as will be apparent, the systems and methods disclosed later herein may be applicable to any installation tool for terminating one or more optical fibers with a fiber optic connector that requires actuation to securely position the one or more field optical fibers in the fiber optic connector.
The installation tool 30 includes a body or housing 32 having an actuation assembly 33 and cradle 36. The cradle 36 is slidable along guide rails 38 inside the body 32 and normally biased toward the actuation assembly 33, as shown in FIG. 3. Prior to inserting a fiber optic connector into the installation tool, the cradle 36 is moved away from the actuation assembly 33. This movement may be achieved by pressing a load button 40, which is operably coupled to the cradle 36 through mechanical linkages (not shown) within the body 32. With the load button 40 depressed (FIG. 4), a user may place a fiber optic connector 10 into the space between the actuation assembly 33 and cradle 36, and subsequently move a lead-in tube 26 of the fiber optic connector 10 axially through a camming member or wrench 34 of the actuation assembly 33 until the cam member 20 is seated in the camming member 34. At this point, the lead-in tube 26 extends beyond crimp arms 44 that are positioned next to the actuation assembly 33. Before inserting a field optical fiber 15 into the lead-in tube 26, the load button 40 is released so that the cradle 36 moves back toward the actuation assembly 33 until the front portion of the fiber optic connector 10 is seated in the cradle 36. A visual fault locator (VFL) assembly 46, the purpose of which will be briefly described below, is also slid toward the fiber optic connector 10 before closing a lid or cover 48 of the installation tool 30 and completing the termination process.
The field optical fiber 15 is eventually inserted into the back of the lead-in tube 26 of the fiber optic connector 10 until it abuts the stub optical fiber 15 (FIGS. 1A and 1B) within the splice components 17, 18. A user then actuates the cam member 20, for example by pressing a cam button 50 operably coupled to the camming member 34 by mechanical linkages (not shown), to bias the splice components 17, 18 together and thereby secure the stub optical fiber 14 and field optical fiber 15 between the splice components 17, 18. At this point the VFL assembly 46 may be used to check the splice connection between the stub optical fiber 14 and field optical fiber 15. The VFL assembly 46 includes an adapter 54, a coupler 60, a jumper (not shown; hidden within the installation tool 30), and an optical power generator (also hidden from view) in the form of a Helium Neon (HeNe) gas laser. The operation of these components is not the focus of this disclosure. Thus, the Corning Cable Systems LLC system/method for verifying an acceptable splice termination, which is commonly referred to as the “Continuity Test System” (CTS), and the combined functionality of the gas laser and jumper, which are commonly referred to as a “Visual Fault Locator” (VFL), will not be further described herein. Reference can instead be made to U.S. Pat. No. 8,094,988, for example, to obtain a more complete understanding of how the installation tool 30 advantageously incorporates continuity testing. Once an acceptable splice termination is verified, the crimp arms 44 are actuated by rotating a crimp knob 52 to secure the lead-in tube 26 onto the field optical fiber 15.
Pressing the cam button 50 to actuate the cam member 20 by means of the camming member 34 moves the camming member 34 from a closed configuration to an open configuration, as shown in FIGS. 5A and 5B. More specifically, the camming member 34 is a spur gear wrench that rotates about the termination axis defined by the stub optical fiber 14 and field optical fiber 15. In a “start” position of the camming member 34 (FIG. 5A), a closed portion of the camming member 34 faces up such that a user must load the fiber optic connector 10 into the camming member in an axial direction from a space between the camming member 34 and cradle 36, as mentioned above. In a “finished” or actuated position of the camming member 34 (FIG. 5B), an open portion of the camming member 34 faces up to allow for easy removal of the fiber optic connector 10 and field optical fiber 15. After moving the VFL assembly 46 back away from the fiber optic connector 10 and then pressing the load button 40, a user can simply grab the fiber optic connector 10 and lift straight up (i.e., away from the body 32).
The movement of the camming member 34 between open and closed positions presents some challenges. In particular, loading the fiber optic connector 10 into the camming member 34 may not be intuitive because of the closed configuration a user sees. Moreover, even if the process for loading the fiber optic connector 10 is known or appreciated, positioning the fiber optic connector 10 between the camming member 34 and VFL assembly 46 and then subsequently moving the fiber optic connector 10 axially into the camming member 34 requires concentration because the opening of the camming member 34 is generally obstructed from view. The space constraints of the installation tool 30 also have the potential to present challenges. These and other factors have the potential to result in the fiber optic connector 10 being loaded into the installation incorrectly, which in turn has the potential to permanently damage the fiber optic connector 10 during the termination process. Therefore, a need exists for installation tools that address these challenges.